Séminaire Ecobio - Lola Gilbert (Observatoire Pelagis, CEB Chizé) - Observatoire Des Sciences De L'Environnement De Rennes (OSERen)

Nutrient flows are a major dynamic component of ecosystem functioning. Essential elements accumulated in the ecosystem are released during the mineralisation of organic matter (OM) by decomposers, making these elements available to primary producers. By digesting essential elements stored in an unavailable form (slowly decomposing living OM) and releasing them in a more available form through the production of faeces and urine, animals facilitate the transfer of these elements to primary producers. In this seminar I will briefly present my PhD thesis, which focused on the role of marine mammals in nutrient cycling. I will then present an ongoing project in collaboration with Ecobio that focuses on the contribution of Kerguelen marine predators to nutrient transfers from the rich and productive waters of the Kerguelen Plateau to the oligotrophic coastal areas of the Kerguelen Islands. We have developed an approach involving 2 study sites, 1 to 3 predator species, 4 ecological compartments (predator waste, soil, plants, invertebrates) and various analytical tools (isotopic analysis, elemental composition analysis, microbial biomass analysis and phenotypic trait measurements) to determine how the seasonal presence of marine predators influences nutrient flows and the structuring dynamics of terrestrial ecosystems close to colonies.